title: Recombinant human prolactin promotes human beta cell survival via inhibition of extrinsic and intrinsic apoptosis pathways.
abstract: OBJECTIVE
  Transplantation of pancreatic islets constitutes a promising alternative treatment for type 1 diabetes. However, it is limited by the shortage of organ donors. Previous results from our laboratory have demonstrated beneficial effects of recombinant human prolactin (rhPRL) treatment on beta cell cultures. We therefore investigated the role of rhPRL action in human beta cell survival, focusing on the molecular mechanisms involved in this process.
  
  
  METHODS
  Human pancreatic islets were isolated using an automated method. Islet cultures were pre-treated in the absence or presence of rhPRL and then subjected to serum starvation or cytokine treatment. Beta cells were labelled with Newport green and apoptosis was evaluated using flow cytometry analysis. Levels of BCL2 gene family members were studied by quantitative RT-PCR and western blot. Caspase-8, -9 and -3 activity, as well as nitric oxide production, were evaluated by fluorimetric assays.
  
  
  RESULTS
  The proportion of apoptotic beta cells was significantly lowered in the presence of rhPRL under both cell death-induced conditions. We also demonstrated that cytoprotection may involve an increase of BCL2/BAX ratio, as well as inhibition of caspase-8, -9 and -3.
  
  
  CONCLUSIONS
  Our study provides relevant evidence for a protective effect of lactogens on human beta cell apoptosis. The results also suggest that the improvement of cell survival may involve, at least in part, inhibition of cell death pathways controlled by the BCL2 gene family members. These findings are highly relevant for improvement of the islet isolation procedure and for clinical islet transplantation.
authors.affiliation: NUCEL, University of São Paulo, São Paulo, Brazil.
authors.forename: L F
authors.initials: LF
authors.lastname: Terra
authors.forename: M H
authors.initials: MH
authors.lastname: Garay-Malpartida
authors.forename: R A M
authors.initials: RA
authors.lastname: Wailemann
authors.forename: M C
authors.initials: MC
authors.lastname: Sogayar
authors.forename: L
authors.initials: L
authors.lastname: Labriola
mesh_terms: D000328:Adult; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D061945:Caspase Inhibitors; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000601:surgery; D006801:Humans; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D016381:Islets of Langerhans Transplantation / Q000379:methods; D008875:Middle Aged; D011388:Prolactin / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D061945:Caspase Inhibitors; D016207:Cytokines; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D051028:bcl-2-Associated X Protein; D011388:Prolactin